I bought a used, almost new, full size 320 45acp from my local gun shop. Factory case & 2 10rd mags. Case is dated March 2, 2017. I pulled the ACU out & it has an Apex trigger bar but appears to be the stock Sig curved trigger. Looking at the FCU closer, it's obvious it has had a trigger job done to it. The contact points look to be polished.
Now I know why the trigger is soooo nice

Will a Sig flat trigger fit an Apex trigger bar?
Grayguns verified theirs will not & Apex said their trigger bars have been redesigned & wouldn't guarantee their flat trigger would fit not knowing the date of my trigger bar